This invention relates generally to digital computer data management systems, and more particularly to improvements in a programmable controller module for facilitating communication between peripheral devices employing different communication disciplines, and between such devices and a data processor.
In almost all data management systems, a controller is designed to accomodate only peripheral devices having a common communication discipline. To accomodate a plurality of peripheral devices of different disciplines, it is necessary to provide a controller of different design for each communication discipline. In typical data management systems, there may be over six types of major network communication disciplines and a multitude of communication disciplines for specialized peripheral devices and terminals. The term "communication discipline" is defined as the protocal or set of rules governing the message format utilized by a particular network, peripheral device or terminal. Exemplary factors distinguishing one discipline from another involve, for example, synchronization, start and end of transfer sequence, message segment length, etc. Each type of discipline requires a different data handling protocol. The term "protocol" is defined as the programmed procedure for inputing and outputing data to and from a network peripheral device or terminal according to the discipline of the data. The following list comprises only a small portion of those disciplines which may be of interest in a typical data management system.
______________________________________ COMMUNICATION DISCIPLINE ______________________________________ VIP VISUAL IMAGE PROJECTION TERMINAL (HONEYWELL) DN355 DATA-NET 355 (HONEYWELL) BAUDOT TTY ITA NO. 2 TELETYPEWRITER ASCII TTY ASCII TELETYPEWRITER ODD OR EVEN PARITY PT-PT BISYNCH POINT-TO-POINT BINARY SYNCHRONOUS RLP300 REMOTE LINE PRINTER 300 (HONEYWELL) GENSER AUTODIN GENERAL SERVICE PORT WUPTC WESTERN UNION PROGRAMMABLE TERMINAL CONTROLLER (AUTODIN) DN30 DATA-NET 30 (HONEYWELL) DACOM DACOM FACSIMILE UNIT 188C TTY MILITARY TELETYPEWRITER DP 2910 DATA PRODUCTS 2910 MIL/ TEMPEST LINE PRINTER D900A VERSATEC PRINTER/PLOTTER DDCMP DIGITAL EQUIPMENT CORPORATION DDCMP ______________________________________
A communication control unit Model BR 1569 manufactured by the Bunker Ramo Corporation employs a programmable controller module for interconnecting peripheral devices of different disciplines to each other and to a data processor comprised of a bus organized central processing unit and a main memory. The complete control unit is described in an application Ser. No. 629,510 filed Nov. 6, 1975, titled "Communication Control Unit." As originally conceived, the Model BR1569 control unit contains firmware in a read-only memory (ROM) of a programmable controller module (PCM) which defines and implements a specific communication protocol for each of 16 channels. A typical system implements three to four protocols with a number of channels assigned to each protocol. A basic problem with that arrangement was that completely new firmware (software entered into a ROM) had to be assembled, delivered and installed each time there was a new channel assignment or a new protocol added.